Authors: Arthur Koestler
The Sleepwalkers (277 page)
*
Copernicus
thought
with
the
ancients
of
the
earth's
axis
as
quasi-mechanically
attached
to
the
orbital
ring
(on
the
analogy
of
the
moon
turning
always
the
same
face
to
the
earth)
and
therefore
had
to
introduce
a
special
motion
to
keep
the
axis
parallel
to
itself
in
space.
†
See
below,
p.
201,
f.
The
count
refers
to
circles
in
general,
that
is
to
say,
eccenters,
epicycles,
deferents,
and
cycloids
to
account
for
rectilineal
oscillations.
Apart
from
the
erroneous
reference
to
34
epicycles,
I
have
nowhere
seen
a
count
made
of
the
number
of
circles
in
De
revolutionibus.
Incidentally,
as
Zinner
has
pointed
out
(op.
cit.,
p.
187)
even
the
famous
count
at
the
end
of
the
Commentariolus
is
wrong
as
Copernicus
forgot
to
account
for
the
precession,
the
motions
of
the
aphelia
and
the
lunar
nodes.
Taking
these
into
account,
the
Commentariolus
uses
38
not
34
circles.
This
was
pointed
out
by
A.
Koyré,
Nicolas
Copernic
Des
Revolutions
des
Orbes
Célestes
(
Paris,
1934),
p.
18
n.
Peurbach,
Epitomae
.
In
his
Theoricae
,
which
is
a
simplified
popular
exposure
of
the
system,
Peurbach
only
gives
twenty-seven
epicycles.
Quoted
by
Professor
Koyré
(in
a
private
communication
to
the
author,
20.12.
1957).
The
reasons
why
Copernicus
had
to
increase
the
number
of
his
circles
are:
(a)
to compensate for the abolition of Ptolemy's equants;
(b)
to
account
for
the
imaginary
fluctuation
in
the
rate
of
precession
and
of
the
value
of
the
obliquity;
(c)
to account for the constant angle of the earth's axis;
(d)
because
he
insisted
on
resolving
rectilinear
oscillations
into
circular
motions
–
which
Ptolemy,
who
was
less
of
a
purist,
did
not
bother
to
do.
This
made
a
total
of
21
additional
epicycles
as
against
a
gain
of
13
(5
from
the
annual
and
8
from
the
diurnal
motion
of
the
earth).
The
editio
princeps
and
the
three
subsequent
editions
(
Nuremberg,
Basle,
Amsterdam
and
Warsaw)
were
based
not
on
Copernicus'
manuscript
but
on
the
copy
made
of
it
by
Rheticus,
which
differed
from
the
manuscript
in
numerous
details.
Copernicus'
original
manuscript
was
only
discovered
in
the
1830's
in
the
library
of
Count
Nostitz
in
Prague.
Nevertheless
the
Warsaw
edition
of
1854
still
followed
the
earlier
ones,
and
only
the
Torun
edition
of
1873
took
account
of
the
discovery
of
the
original.
Butterfield,
op. cit., p. 30.
De
revolutionibus, Lib. I, Cap. 9.
Ibid.,
Lib. I, Cap. 8.
H.
M.
Pachter,
Magic
into
Science
(
New
York,
1951),
pp.
26,
30.
Letter
against
Werner
,
Prowe
II,
p.
176
f.
An
English
translation
was
published
by
Rosen,
op.
cit.
Rheticus,
Ephemerides
Novae
(
Leipzig,
1950),
quoted
by
Prowe
II,
p.
391.
The
last
observation
of
his
own
(an
eclipse
of
Venus
by
the
moon)
which
he
used
in
the
Revolutions
was
made
in
March
1529.
The
book
went
to
the
printers
in
1542.
During
the
intervening
thirteen
years,
Copernicus
continued
to
make
observations
and
jotted
down
twenty-two
results,
but
he
did
not
use
these
in
the
Revolutions
.
This
enables
us
to
determine
the
date
of
the
completion
of
the
manuscript
with
reasonable
certainty.
It
must
have
been
completed
after
1529,
since
the
Venus
observation
just
mentioned
is
entered
in
the
body
of
the
text.
It
is
unlikely
that
it
was
completed
later
than
1532,
since
observations
made
in
that
year
are
not
entered
into
the
text,
but
inserted
on
a
separate
leaf.
He
continued to make corrections and alterations in subsequent years,
but these were of a minor character.
The
statement
in
the
dedication
to
Paul
III
that
he
withheld
his
work
for
"four
times
nine
years"
cannot
be
taken
literally.
(It
is
actually
an
allusion
to
Horace
Epistle
ad
Pisonus.)
He
evidently
brought
the
heliocentric
idea
back
from
Italy
when
he
returned
to
Ermland
in
1506
–
which
happens
to
be
almost
precisely
four
times
nine
years
before
he
published
the
Revolutions;
the
details
of
the
system
must
have
been
gradually
taking
shape
in
his
mind
between
that
earlier
date
and
1529.
He
was
then
in
his
middle
fifties,
and
after
that
made
no
serious
attempt
to
revise
his
theory.